Rice straw based silicon nanoparticles improve morphological and nutrient profile of rice plants under salinity stress by triggering physiological and genetic repair mechanisms

Abstract

The agricultural sector is facing numerous challenges worldwide, owing to global climate change and limited resources. Crop production is limited by numerous abiotic constraints. Among them, salinity stress as a combination of osmotic and ionic stress adversely influences the physiological and biochemical processes of the plant. Nanotechnology facilitates the production of crops either directly by eradicating the losses due to challenging environmental conditions or indirectly by improving tolerance against salinity stress. In this study, the protective role of silicon nanoparticles (SiNPs) was determined in two rice genotypes, N-22 and Super-Bas, differing in salinity tolerance. The SiNPs were confirmed through standard material characterization techniques, which showed the production of spherical-shaped crystalline SiNPs with a size in the range of 14.98-23.74 nm, respectively. Salinity stress adversely affected the morphological and physiological parameters of both varieties, with Super-Bas being more affected. Salt stress disturbed the ionic balance by minimizing the uptake of K⁺ and Ca²⁺ contents and increased the uptake of Na⁺ in plants. Exogenous SiNPs alleviated the toxic effects of salt stress and promoted the growth of both N-22 and Super-Bas, chlorophyll contents (16% and 13%), carotenoids (15% and 11%), total soluble protein contents (21% and 18%), and the activities of antioxidant enzymes. Expression analysis from quantitative real-time PCR showed that SiNPs relieved plants from oxidative bursts by triggering the expression of HKT genes. Overall, these findings demonstrate that SiNPs significantly alleviated salinity stress by triggering physiological and genetic repair mechanisms, offering a potential solution for food security.

Keywords: HKT transporters; Oxidative stress; Rice; Salinity stress; SiNPs.